1981 Honda CB750F Overheating

[honda_newbie]

So, I've just gotten my CB750 rebuilt and running.  However, it is running WAY too hot.  It's making the gas tank heat up as well.  

Another issue is that white smoke is coming out from the air vents on the right side of the bike once it gets nice and warmed up.  It gradually begins to smoke more and more and starts to creep up under the seat and possibly the airbox. (Couldn't quite diagnose the start point of the smoke from the airbox).

*** I think the primary issue may be that I switched out the tank for a 1982 CB900F thus resulting in a larger fuel valve.  I've taken a look at the separate valves and the 82' cb900F has a much larger spout than the 81' cb750f.  Obviously, I'm thinking that may be dumping more fuel and causing this issue.  I just want to run it by you guys.  Any help would be much appreciated!

Here's a picture of the build :

[motogrady]

These aren't water cooled.
You can't just let it sit and idle or run for 20 minutes without air going over the fins.
One of those 12 dollar square house fans sitting in front of the motor is what I use when working on it in the shop.

Someone said they got an infrared gun from Home Depot. 50 bucks.
Point it at the exhaust pull the trigger and you got exhaust temp.
I think they were seeing around 600 degrees F each cylinder.

Nice bike btw.

[TOOLS1]

The petcock is only an on/off valve, and has nothing to do with regulating how much fuel is being used. The things that regulate fuel usage is the jets. When you did the build, were the carbs rebuilt? Was the engine rebuilt? The main things that can make your bike run hot are, running too long without airflow (which Motogrady pointed out), a vacuum leak, too lean of jetting, timing off, cam timing off.
TOOLS

[honda_newbie]

I have had the carbs and engine fully rebuilt

[TOOLS1]

OK, now we have a lot to work with. First we need to figure out if it is smoking because it is overheating, or if you have an internal engine problem such as a broken ring. Then we need to figure out why it is overheating. I already listed some of the causes, but since the carbs were also rebuilt here are some things to check. Is there a vacuum leak? Are the little O-rings and washers on the fuel screws installed properly? I find these two problems all the time after someone has removed, rebuilt, and reinstalled the carbs.
TOOLS

[honda_newbie]

Sorry for the delay.  Turns out the bike was just burning off the years of fuel leakage.  I took it out for a small ride and it stopped smoking towards the end of it.  Thanks for all the input